Third Mars Polar Science Conference (2003) 8117.pdf

VAST ATMOSPHERIC COLD TRAPS WITHIN THE LARGE RINGED TOPOGRAPHIC FEATURES IN NE : IMPLICATION FOR MARS. G. A. Burba, Vernadsky Institute of Geochemistry and Analytical Chemistry, 19 Kosygin St., Moscow 119991, e-mail: [email protected]

Introduction: The ridges within the vast mountain plained that each of these “cold poles” is located country of the NE Siberia have been revealed recently within the lower areas at the central parts of the large to comprise two giant ring structures (RS), 500 and ring structures (intermountain basins), which works as 400 km in diameter [1] . Such evidence is a new look a giant cold traps being enclosed within a ring wall of on the general topographic structure of the area and mountain ridges. Such situation could lead to the cir- could be of importance for climatic consequences.The cumstances of the temperature inversion in the near- central lower areas of these structures, which are en- surface layer of the atmosphere. closed within a ring wall of mountain ridges, work as Implication for Mars: Couldn’t the similar situa- giant “cold traps” for the atmospheric air. During the tion with the air temperature take place during the win- winter seasons the temperature inversion in the near- ter season within the craters and large basins in the surface layer of the atmosphere take place there. polar regions of Mars? Topographic description: The highest area of the References: [1] Burba G. A. (1995) LPSC XXVI, North-East Siberia, Russia, consists of the mountain 189-190. [2] Atlas SSSR (1984) Map “Air tempera- ridges arranged as the two adjacent RS. These RS are ture”, 99 (Atlas of the USSR – In Russian). located between Lena River Mouth and Magadan Coast of the Sea of Okhotsk. Each of the two rings have circu- lar pattern of mountain ranges, which encircle a pla- teau area in the central part of the ring. The general topographic shape of each RS is a complex of high mountain rings (altitudes 1000 to 3000 m) with a lower, but still topographically high (400-1200m) pla- teau inside, and lowland plains outside (50-200 m). The outer diameter of each structure is about 700 km. The rim crest diameters are about 500 km for Yana Ring Structure (YRS), NW in the couple, and 400 km for Oymyakon Ring Structure (ORS), SE one. YRS is located between 63 and 70°N, 125 and 140°E, and ORS – between 61 and 67°N, 136 and 151°E. In gen- eral YRS is somewhat lower than ORS, especially with its inner area. The structures are named after the Yana River and Oymyakon settlement, which are located within each of the them. Air temperature data: The weather observations at on Yana River, near the center of YRS, and at Oymyakon on River, near the center of ORS, have determined as early as in 1930s that these areas are the coldest places at the Northern hemisphere of the Earth with the minimal records of air temperature as low as – 68° C at Verkhoyansk and – 71° C at Oymyakon. Further long-term meteorologi- cal data revealed the areas of Verkhoyansk and Oymy- akon as the enclosed regions with very low air tem- peratures in winter. Both areas have value of the mean monthly air temperature for January defined as “lower than – 48° C” [2]. And over the whole NE Asia such low values are typical ONLY to these two areas, the central parts of YRS and ORS. Interpretation: Now, after a new look at the to- pographic structure of the NE Siberia, it could be ex-